Latency Can Become An Oracle
A shared prefix cache improves throughput, but a tenant can probe response time to learn whether another request populated a matching prefix.
cacheisolate replays ordered multi-tenant traffic under shared, fully isolated, and sensitivity-aware cache policies with explicit ownership.
The Demo
The shared policy identifies the secret alpha prefix through an 86 ms hit-miss gap. Selective isolation removes that inference while retaining one approved cross-tenant reuse event, equal to 50% of the shared reuse in the fixture.
The simulator establishes the policy tradeoff, not a universal timing threshold. Real serving stacks need jitter modeling, concurrency tests, authentication, and cache-key review.
Research Basis
Recent work demonstrates practical privacy leakage through shared LLM KV and prefix caches and motivates tenant-aware isolation.
Read the NDSS 2025 KV-cache leakage study.